Polymers containing phosphorylcholine groups have been developed as biocompatible materials. Polymers having phosphorylcholine groups have been synthesized mainly as follows: acryl type monomers mainly having hydroxyl groups and 2-chloro-1,3,2-dioxaphosphorane-2-oxide are brought into reaction and then trimethylamine is used to turn the reaction product into quaternary ammonium to synthesize monomers having a phosphorylcholine structure, which are then polymerized (refer to the following Patent Documents, for example).
Patent Document 1 describes the preparation of a copolymer of 2-methacroyloxyethylphosphorylcholine and methacrylate, and Patent Document 2 describes the preparation of a homopolymer of 2-methacryloyloxyethyl phosphorylcholine.
Patent Document 3 discloses a cosmetic in which powder coated with a homopolymer or copolymer of 2-methacryloyloxyethyl phosphorylcholine is used as a cosmetic powder to improve moisture retention and adhesion on the skin.
Patent Document 4 describes a polymer prepared by means of the graft polymerization of 2-methacryloyloxyethyl phosphorylcholine on water soluble cellulose; this polymer is utilized as a polymer having blood compatibility.    Patent Document 1: Japanese Patent Laid-Open H9-3132 bulletin    Patent Document 2: Japanese Patent Laid-Open H10-298240 bulletin    Patent Document 3: Japanese Patent Laid-Open H7-118123 bulletin    Patent Document 4: Japanese Patent Laid-Open H5-345802 bulletin
A polyalkylsiloxane having phosphorylcholine groups in its main chain has not been reported.
Due to the monomer solubility issues when introducing the hydrophobic groups into the polymer, the polymer preparation method in which monomers having a phosphorylcholine group are polymerized requires the use of an organic solvent known as a chain transfer catalyst such as methanol, ethanol, and chloroform as a polymerization solvent, which makes it difficult to produce high molecular weight polymers.
Also, there is a problem in that the steric hindrance of the phosphorylcholine group reduces the polymerization yield or makes it impossible to obtain the desired polymer
Also, the monomer synthesis reaction has to be conducted under strictly anhydrous conditions, which complicates the technique.
In view of the description above, the inventors conducted earnest research to obtain a polysiloxane that has a wide application range in biocompatible materials and cosmetic ingredients, and completed the present invention by discovering that a polysiloxane having a phosphorylcholine group can be obtained easily and with a high versatility by reacting a compound containing phosphorylcholine groups with a polysiloxane having a functional group that reacts with this compound, which leads to a macromolecular reaction in the main chains or side chains of the polymer.